The feeding of a liquid enteral nutritional product from a hangable container, such as a bottle or a plastic bag with a bottom outlet connecting to a drip chamber and the latter to a flexible tubing, or lumen, leading to a nasogastric tube or a feeding tube inserted through a gastrostomy or a jejunostomy, by gravity flow or aided by a pump, is well known. The liquid enteral nutritional product may be aseptically processed or terminally retorted, and may be supplied in a pre-filled, ready-to-hang container, or placed in such a container by a caregiver. However, the selection of diets, particularly special diets, from amongst the rather modest number of typically available liquid enteral nutritional products is limited. This narrows, as a practical matter, the choices of the attending physician as to diet modifications, temporary or long term, that might significantly benefit the patient. In view of the now-recognized importance of providing aseptic nutritional compositions, it can be seen that modified diets are not easily prepared without observing the stringent requirements needed to deliver an aseptic nutritional composition to the patient. The need to observe such requirements has heretofore militated against preparing small quantities of special diets designed for a specific patient.
Moreover, a number of nutrients as well as medicaments, diagnostic agents, and other ingredients such as probiotics, that at any given time might be desirable to orally administer to a patient are not stable during heat sterilization or may not be mutually compatible with other desired ingredients for an extended period of time, such as days or even months until used, and thus are not readily amenable to large scale preparation and consequent storage as the product moves through commerce.
Although it has been the practice for some time to use a container, such as a hangable container, to deliver a liquid enteral nutritional product through a drip chamber and connecting flexible tubing to a feeding device such as a feeding tube extending into the gastrointestinal tract of a patient, so far as is known, there has been no attempt to utilize the drip chamber as a formulation chamber in such a feeding system and to add ingredients such as medicaments or additional nutrients to a flowing enteral nutritional product at the time of administering the nutritional product to the gastrointestinal tract of a patient. Liquid enteral nutritional products currently on the market are described in the reference text "Nutrition In Critical Care", Gary P. Zaloga, ed., Mosby--Year Book Inc., St. Louis, Mo., 1994, at Chapter 24, authored by Barbara Hopkins, Part III, "Feeding", pp. 439-467. This reference indicates that complete nutrient compositions contain proteins, carbohydrates, fibers, fats, and vitamins and minerals in an aqueous medium.